UN report: Without action, climate change effects will be ‘irreversible’

The United Nations warned Sunday that the world must get most of its energy from renewable sources by 2050, or increase the likelihood of what it called “severe, pervasive and irreversible damage.”

“Science has spoken, there is no ambiguity in their message,” said U.N. Secretary-General Ban Ki-moon at the Intergovernmental Panel on Climate Change (IPCC) in Copenhagen, Denmark on Sunday. “Leaders must act, time is not on our side.”

The 40-page report, which evaluated around 30,000 scientific publications, found that there was more than a 95 percent chance that humans have been the leading cause of global warming since the 1940s and 50s.

Another key finding: Each of the last three decades have been warmer than the one that came before it. More than 90 percent of that heat, or energy, has been accumulated by the world’s oceans between 1971 and 2010, which seem to be bear the brunt of climate change, the report detailed.

Another concern was emissions of greenhouse gases such as carbon dioxide, which grew faster between 2000 and 2010 than in previous decades.

By cutting greenhouse gases to zero by 2100, the world would limit the risks of irreversible damage caused by climate change, the report said.

In late September, Ki-moon brought together government leaders, finance officials and others for a one-day UN Climate Summit.

Ahead of the summit, hundreds of thousands of people participated in climate marches in New York City and in cities throughout the world where organizers highlighted scientific findings.

In March, PBS NewsHour’s Hari Sreenivasan spoke with Professor Georffrey Dabelko, one of the authors of the latest IPCC report on climate change and its impacts on human security. You can watch the discussion here.

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Carey Reed assists in covering breaking and feature news for NewsHour Weekend's website. She also helps the NewsHour Weekend broadcast team in the production of the show. She is interested in the flourishing fields of data journalism and information visualization and recently graduated, with honors, from Columbia University’s Graduate School of Journalism.